A problem that arises with open-end spinning apparatus of this type is the unsatisfactory deposit of the fibres in the region of the tail end of spun yarn for incorporation therein.
One example for achieving an improved deposit of fibres is disclosed in British Pat. No. 1,524,659 and comprises two closely spaced apart perforated suction drums which rotate in the same direction and define between them a throat into which the fibres are fed from fibre feeding means and formed into a yarn. Disposed in the path of the fibres between the fibre feed means and the throat is a toothed disc or throwing member arranged for rotation in a plane transverse to the direction of movement of the fibres. The fibres, it is said, impinge upon and are deflected by the teeth on the rotating disc so that they are orientated to lie in a direction parallel to the movement of the spun yarn.
A disadvantage of this solution is that some of the fibres wrap around the teeth so that they tend to be removed from the mainstream of fibres, which is unacceptable. With this solution it is not possible to locate the rotating disc close to the yarn formation zone because of the physical limitations imposed by the rotating drums. Thus after contact with the teeth the fibres would lose the parallel orientation before reaching the yarn formation zone. Furthermore, the provision of a rotating disc requires additional drive means, thereby complicating the apparatus and introducing a source of possible failure to the system.
In a further known proposal disclosed in U.S. Pat. No. 4,130,983, referring particularly to the apparatus disclosed in FIGS. 6a and 6b, a pair of closely spaced apart perforated suction drums, which rotate in the same direction, define between them a throat into which the fibres are fed from fibre feed means through a fibre feed duct. An air injector is provided adjacent the peripheral surface of the beater at the entrance end of the fibre feed duct. The fibre feed duct is inclined so that fibres conveyed therethrough move with a component of direction the same as that of the withdrawn yarn. However, it is believed that in practice this arrangement will not orient the fibres to the best advantage.
In a further known proposal U.S. Pat. No. 4,168, 601 discloses a detailed openend spinning system of this general type, but does not give particular reference to the problem of proper orientation of fibres within the yarn as it is spun.
Additionally a very early system of this general trend is disclosed in British Pat. No. 1,231, 198. However this proposal had a number of serious faults and could not successfully spin an acceptable yarn.